Tetramethylthiuram disulfide vulcanization of extracted rubber. V. Low molecular products and the mechanism of zinc oxide activation

Craig, D. P.; Davidson, W.; Juve, A. E.

doi:10.1002/pol.1951.120060205

Cited by 32 publications

(9 citation statements)

References 13 publications

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“…In the past the opinion has been that TMTD vulcanizes via the intermediate formation of TMTM and active sulfur 83 Another approach for sulfur donor vulcanization was the use of model compounds. It has been suggested that thiuram disulphides function during cure by decomposition to yield active sulfur and ZDC, which together constitute an accelerated sulfur system.…”

Section: Rubbermentioning

confidence: 99%

Recent Developments in Crosslinking of Elastomers

Aprem

Joseph²,

Thomas

2005

Rubber Chemistry and Technology

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The recent developments in the vulcanization of elastomers, major types of crosslinking, and mechanism of crosslinking have been reviewed. Attention has been made to sum up the accelerated vulcanization. Possible mechanisms by which the reaction is taking place are discussed. The role of accelerators, activators, and fillers has been described. The different types of crosslinks and importance of each type on the specific properties of the resulting vulcanizates, etc., are discussed. Various aspects of vulcanization like model compound vulcanization, nitrosamine generation, etc., are discussed. The importance of binary accelerators and possible mechanism of their action have been mentioned. The method of double network formation, which is useful for the improvement in properties, is also described. The different methods for characterization of networks and different methods for estimating crosslink densities are also explained.

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Section: Rubbermentioning

confidence: 99%

Recent Developments in Crosslinking of Elastomers

Aprem

Joseph²,

Thomas

2005

Rubber Chemistry and Technology

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“…With tetramethylthiuram disulfide (TMTD)‐accelerated sulfur vulcanization, Coran6, 8 found a decrease in the rate of reaction if the stearic acid concentration was increased. Palmitic acid has a mild activating effect 9…”

Section: Introductionmentioning

confidence: 99%

Effect of carboxylic acids on 2-bisbenzothiazole-2,2?-disulfide- and tetramethylthiuram disulfide-accelerated sulfur vulcanization. IV. Vulcanization of polyisoprene compounds with ZnO

McGill

Shelver

1999

J. Appl. Polym. Sci.

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ABSTRACT:The effect of benzoic and stearic acids on 2-bisbenzothiazole-2,2Ј-disulfide (MBTS)-and tetramethylthiuram disulfide (TMTD)-accelerated sulfur vulcanization of polyisoprene compounds, containing ZnO, was studied at 150°C. In the presence of ZnO, the acids are rapidly converted to their zinc salts that, unlike the acids, do not attack accelerator polysulfides and, instead, promote vulcanization. The addition of accelerator polysulfides to the chain is not affected by zinc salts, but the rate of crosslinking of pendent groups is facilitated. In MBTS vulcanization, the promotion of crosslinking reactions reduces the number of pendent groups involved in cyclization reactions and higher crosslink densities are attained. In TMTD compounds, crosslink densities are increased on addition of ZnO and of ZnO/carboxylic acids. A mechanism is suggested to account for the promotion of crosslinking by the zinc salts. Bis(2-mercaptobenzothiazolo)zinc(II) and bis(dimethyldithiocarbamato)zinc(II) can act similarly to zinc benzoate or stearate to promote the crosslinking of pendent groups, but are less efficient. With benzoic acid, a limited attack by zinc benzoate on TMTP leads to a slightly lower increase in crosslink density than is achieved with the addition of ZnO alone.

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“…Some investigations have also been carried out on the effect of MBTS-ZDC binary combinations upon the vulcanization of NR. The results are shown in Table I1 (mixes 1, [10][11][12][13]. It is evident that, like MBTS and CBS, MBT is also capable of exhibiting enhanced activity with regard to torque, modulus, and tensile strength in the presence of ZDMC or ZPDC.…”

Section: Resultsmentioning

confidence: 99%

Studies on cure synergism. I. Effect of safe zinc dithiocarbamates on NR vulcanization accelerated by thiazole‐based accelerators

Debnath

Basu

1994

J of Applied Polymer Sci

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SYNOPSISInvestigations have been carried out on the effect of several zinc dithiocarbamates in the presence of thiazole-based accelerators in the vulcanization of natural rubber (NR) , keeping in mind the possibility of introducing safe dithiocarbamates derived from safe amines. Mutual activity is observed in all the binary systems studied, the highest being observed in the zinc dibenzyldithiocarbamate-dibenzothiazyldisulfide ( ZBEC-MBTS ) -accelerated system. The effect of zinc diisopropyl dithiophosphate, reportedly a safe rubber additive, which is recognized as an age-resistant agent for NR, on cure has also been studied. The study reveals that thiuram disulfide and MBT are always formed from the reaction either between zinc dithiocarbamate (ZDC) and MBTS or between ZDC and N-cyclohexyl-2-benzothiazole sulfenamide (CBS) . It has been conclusively proved that Z-mercaptobenzothiazole (MBT) generated from MBTS or CBS reacts with ZDC and produces tetramethyl thinram disulfide (TMTD). The observed mutual activity has been discussed based on the cure and physical data and explained through the results based on HPLC and a reaction mechanism. 0 1994 John Wiley & Sons, Inc. I NTRO DU CTlO NMost of the secondary amines have been shown to produce nitrosoamines, which are believed to be carcinogens.' A significant amount of rubber chemicals is obtained from these secondary amines. In fact, a recent survey shows that these rubber additives and the vulcanizates obtained from these chemicals contain varying proportions of nitrosoamines.2 The present investigation aims at finding some rubber accelerators based on zinc dithiocarbamates ( ZDCs) that are widely used in the preparation of technological vulcanizates, especially in latex goods and cable compounds. ZDCs do not impart odor or taste to the resulting vulcanizates that exhibit good aging behavior. It has been reported3 that ZDCs act as booster accelerators when they are combined with N-cyclohexyl-2-benzothiazole sulfenamide (CBS) , 2-mercaptobenzothiazole (MBT) , * To whom correspondence should be addressed. and dibenzothiazyldisulfide (MBTS ) . These binary systems of accelerators find applications in the vulcanization of diene elastomers and slow-curing butyl rubber. However, systematic investigations in this regard are lacking and the available information is very scanty. In the present investigation, it was our endeavor to prepare ZDCs from safe amines and to study their boosting effect in the presence of other accelerators during the vulcanization of rubber. EXPERIMENTAL

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Tetramethylthiuram disulfide vulcanization of extracted rubber. V. Low molecular products and the mechanism of zinc oxide activation

Cited by 32 publications

References 13 publications

Recent Developments in Crosslinking of Elastomers

Recent Developments in Crosslinking of Elastomers

Effect of carboxylic acids on 2-bisbenzothiazole-2,2?-disulfide- and tetramethylthiuram disulfide-accelerated sulfur vulcanization. IV. Vulcanization of polyisoprene compounds with ZnO

Studies on cure synergism. I. Effect of safe zinc dithiocarbamates on NR vulcanization accelerated by thiazole‐based accelerators

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